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FreeBSD-SA-00:43                                           Security Advisory
                                                                FreeBSD, Inc.

Topic:          brouted port allows gid kmem compromise

Category:       ports
Module:         brouted
Announced:      2000-08-28
Credits:        Discovered during internal auditing
Affects:        Ports collection prior to the correction date.
Corrected:      2000-08-22
Vendor status:  Contacted
FreeBSD only:   NO

I.   Background

brouted is a dynamic routing daemon.

II.  Problem Description

The brouted port is incorrectly installed setgid kmem, and contains
several exploitable buffer overflows in command-line arguments. An
attacker exploiting these to gain kmem privilege can easily upgrade to
full root access by manipulating kernel memory.

The brouted port is not installed by default, nor is it "part of
FreeBSD" as such: it is part of the FreeBSD ports collection, which
contains over 3700 third-party applications in a ready-to-install
format. The ports collections shipped with FreeBSD 3.5-RELEASE and
4.1-RELEASE contain this problem, since it was discovered after the
releases during internal auditing.

FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.

III. Impact

Unprivileged local users can obtain group kmem privileges, and upgrade
further to full root privileges.

If you have not chosen to install the brouted port/package, then your
system is not vulnerable to this problem.

IV.  Workaround

Execute the following command as root to remove the setgid bit on the
/usr/local/sbin/brouted file:

# chmod g-s /usr/local/bin/brouted

V.   Solution

One of the following:

1) Upgrade your entire ports collection and rebuild the brouted port.

2) Deinstall the old package and install a new package dated after the
correction date, obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/net/brouted-1.2b.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/net/brouted-1.2b.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/net/brouted-1.2b.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/net/brouted-1.2b.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/net/brouted-1.2b.tgz

NOTE: It may be several days before updated packages are available. Be
sure to check the file creation date on the package, because the
version number of the software has not changed.

3) download a new port skeleton for the brouted port from:

http://www.freebsd.org/ports/

and use it to rebuild the port.

4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:

ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-3-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-4-stable/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/i386/packages-5-current/devel/portcheckout-2.0.tgz
ftp://ftp.FreeBSD.org/pub/FreeBSD/ports/alpha/packages-5-current/devel/portcheckout-2.0.tgz

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